Articles such as automotive parts or castings are sometimes cleaned by a stream of abrasive particles such as shot directed against the articles as they are advanced through a cleaning zone. In order to ensure complete and effective contact of the abrasive stream against all portions of each article as it passes through the zone, the blast heads supplying the abrasive stream may be oscillated transverse to the direction of flow of the articles, and the articles themselves may be tumbled, for example by rotating the drum about its longitudinal axis. Preferably, to ensure complete abrasive contact and cleaning, both tumbling of the articles and oscillating of the abrasive blast heads can be employed together.
Unfortunately, the use of both of these expedients at the same time has diminished their individual effectiveness. As the drum through which the articles pass during cleaning is rotated about its longitudinal axis to tumble the articles, the sides of the drum can interfere with the stream of abrasive from the blast heads, particularly when the blast heads are oscillated to their extreme lateral position. Removal of portions of the sides of the treatment drum to accommodate the full stream of abrasive exposes a greater portion of the interior of the drum to the abrasive stream, but permits a portion of the articles being cleaned and the abrasive to spill out of the drum as it and the blast heads rotate.
One solution has been to provide jointed or hinged rigid side members for the drum which travel along guide members to provide a variable opening into the drum to accommodate the abrasive stream from the oscillating blast heads. Such systems, however, involve complexity and extensive frictional contact, resulting in wear and requiring frequent replacement and added expense.
There is, therefore, a need for an improved oscillating abrasive blast device which achieves the benefits of optimal oscillation of the drum and abrasive blast head while avoiding excess friction and wear and while maintaining the integrity of the drum and enhanced contact of the abrasive stream and articles being cleaned.